For instance, credit cards, bank cards, tradable coupons, and ID cards, all likely to incur hassles when illegally copied, doctored and used, should desirously have an authentication function by themselves. In addition, for instance, wristwatches, leather goods, upscale objects such as noble metal goods and jewelry, especially those called upscale brand products, audios, electric appliances, and music, image, game or computer software recorded in media which used to be illegally copied, too, should desirously have an authentication function by themselves.
So far, much use has been made of holograms for the purpose of authenticating various objects including the above goods or articles, primarily because of a sophisticated structure and, hence, difficulty of fabrication. However, how to fabricate holograms has been known to experts in the art, and it is still fairly difficult to tell genuine holograms from false ones because of sophistication.
As a hologram substitute, therefore, it has been proposed to use an authentication medium comprising a substrate, a light selective reflecting layer that is provided on one surface of the substrate and capable of selectively reflecting only one of left-handed or right-handed circularly polarized light of incident light, and an authentication segment that is formed on at least a part of the light selective reflecting layer and has authentication information (for instance, see patent publication 1).                Patent Publication 1        JP(A) 2000-25373 (pages 3-5, FIG. 1)        
The authentication set forth in patent publication 1 still makes use of an authentication segment made up of an embossed hologram and so allows a precise pattern to be formed as an authentication segment; however, the time of contact of an embossing mold with the material to be embossed must be long enough to fully reproduce a hologram pattern embossed in the embossing mold. Thus, it is difficult to cut down fabrication time, and an increased step counts for the embossing mold itself works against alteration of the pattern at the authentication segment.